湿式连接装配式混凝土框架抗连续倒塌静力试验研究

梁柱节点连接在大变形下的承载和变形能力对装配式混凝土框架结构抗连续倒塌性能具有显著影响。对4个不同湿式节点连接的装配式混凝土框架试件和1个现浇试件进行了静力连续倒塌试验，其中梁采用了机械套筒、弯起锚固和预应力连接，柱采用套筒灌浆和浆锚搭接连接。研究发现：采用机械套筒时梁钢筋在套筒处集中断裂，试件在压拱机制和悬链线机制下的倒塌抗力均显著降低；梁钢筋采用弯起锚固时，试件受力行为和倒塌抗力与现浇试件基本一致；预应力能够显著提升试件在两个机制下的倒塌抗力，但是在极限倒塌变形下预应力锚具传递较大的集中力，导致节点区混凝土的局部劈裂破坏；柱钢筋的套筒灌浆和浆锚搭接连接能够承受连续倒塌大变形下的水平剪力作用，但是柱接缝灌浆层在显著的水平剪力作用下发生滑移，减弱了柱对梁的约束；机制转换时，压拱机制轴压力对试件倒塌抗力产生负贡献；机械套筒和预应力连接试件的梁轴力对倒塌抗力贡献比例分别高于和低于现浇混凝土试件。

Static progressive collapse test on prefabricated concrete #br# frames with wet connections

The loading and deformation capacities of beam-column joints under large deformation have a significant impact on the progressive collapse performance of prefabricated concrete frame structures. A static progressive collapse test was conducted on four prefabricated concrete frame specimens with different wet connections and one cast in situ specimen. Mechanical sleeves，bent-up steel bar anchorage and prestressing tendon were used as the connections of beam reinforcement，while rebar splicing by grout-filled coupling sleeve and rebar lapping in grout-filled hole were used as the connections of column reinforcement. It is found that all bottom reinforcing bars in the beam fractured simultaneously at the same location of one sleeve when the mechanical sleeves were used，which significantly reduced the collapse resistance of the specimen under the compression arch mechanism and the catenary mechanismWhen the beam reinforcement was bent up and anchored in concrete，the mechanical behavior and collapse resistance of the specimen were very similar with those of the cast-in-situ specimen. The prestressing tendon significantly improved the collapse resistance of the specimen under the two mechanisms，but local splitting failure of concrete in the joint was induced by the concentrated load transferred from the prestressed anchors under the ultimate deformationThe rebar splicing by grout filled coupling sleeve and the rebar lapping in grout-filled hole of the column steel bars were capable to withstand the horizontal shear force under large deformation in progressive collapse，but shear-slip of the column jointgrouting layer was found when exposed to the significant horizontal shear force，which in turn weakened the constraint of the column to the beam. When the collapse-resisting mechanism was transformed from the compression arch mechanism to the catenary mechanism，the axial compressive force of the compressive arch mechanism negatively contributed to the collapse resistance of the specimen. The contribution of axial force to collapse resistance of the specimens connected by mechanical sleeves and prestressing tendon were respectively higher and lower than that of the cast-in-situ concrete specimen.